There is a large price difference, but what would my resulting image difference be if i took the N4 over the N6?

Also, if I do use either or, what if im pushing my video into the unti with RCA cable? Will that make a large difference?

Or better yet, buying a 20 dollar TV card for a spare computer and using that?

Component inputs are the major difference. Essential in my book. Composite/svid may look ok on a low resolution device like a television but when you take a high resolution device and make it 10' wide it's gonna suck.